Square tube cap



FIG. 1 is a top plan view according to the invention;

FIG. 2 is a bottom plan view according to the invention;

FIG. 3 is a front, bottom right perspective view according to the invention;

FIG. 4 is a back, top right perspective view according to the invention;

FIG. 5 is a front view according to the invention and the back view being a mirror image thereof; and,

FIG. 6 is a right view according to the invention and the left view being a mirror image thereof. 

The ornamental design for a square tube cap, as shown and described. 